The invention relates to a reproduction apparatus for double-sided recording media without any reversal of the direction of rotation or changing or turning over of the recording medium, such as for example a digital versatile disc, also referred to as DVD. In this case, recording media, which are pre-recorded on both sides, are designated as double-sided recording media.
In the case of a DVD, it is possible for example for both sides of the disc to be pre-recorded. If such a disc is inserted into a customary reproduction apparatus, the reproduction apparatus can generally access only one side of the disc and the reproduction apparatus can read only one side of the double-sided disc. If the other side is to be read or reproduced, then the disc has to be taken out, turned over and reinserted.
However, reproduction devices for double-sided recording media are already known as well, in which one or two scanning devices is or are used to read both the top side and the underside of the recording medium. Since double-sided recording media are generally intended also to be suitable for reproduction in reproduction apparatuses which reproduce only one side of a recording medium, a spiral track of the recording medium is provided in such a way that it has a fundamentally corresponding progression, with reference to a direction of rotation of the disc turntable on which the recording medium rests, even after the side has been changed over. Therefore, in order to reproduce double-sided recording media in reproduction apparatuses with two-sided scanning of the recording medium, the direction of rotation of the recording medium is reversed in order to carry out reproduction of information stored on the recording medium in a chronological order. In order to change over the reproduction from one side to the other side, it is necessary, therefore, firstly to stop the disc turntable rotation and then to accelerate it in the opposite rotational direction. This operation not only requires a corresponding period of time for which reproduction is interrupted, but also leads to a corresponding expenditure of energy, necessary for braking and accelerating the disc turntable including recording medium.
A reproduction apparatus for double-sided recording media enables double-sided recording media to be reproduced without any reversal of the direction of disk rotation or changing or turning over of the recording medium.
The invention facilitates reproduction of double-sided recording media without any reversal of the direction of rotation or changing or turning over of the recording medium. Usually the reproduction of recording media in reproduction apparatuses which scan on one side, is facilitated by the recording medium being changed or turned over, or in reproduction apparatuses which scan on both sides, by the direction of rotation being reversed.
In an inventive arrangement a reproduction apparatus is provided in such a way that one side of the recording medium is scanned in the customary manner, as is known from reproduction apparatuses which scan on one side, and the other side of the recording medium is scanned, without any reversal of the direction of rotation or changing or turning over of the recording medium, by being read backwards portion by portion or section by section. A track portion or section is a section that is scanned or read between two jumps of the scanning device. The scanned data are buffer-stored and the buffer-stored track portion is reversed bit by bit. That bit of the entire track portion which was read first consequently becomes the last bit, the next bit of the entire track portion that was read in becomes the penultimate bit, and so on. Once the bit-by-bit reversal of the track portion has been concluded, the correctly orientated data of this track portion are available.
The converted data are then utilized conventionally or analogously to the other side of the recording medium. In order to ensure the data rate necessary for reproduction even in the course of backwards reading portion by portion, a higher read-in data rate is necessary on account of the additional jumps of the scanning device, which data rate is already provided in the case of reproduction apparatuses that already scan at multiple speeds or is achieved by increasing the rotational speed of the recording medium.
In principle, a complete track portion is read in order to be able to utilize this track portion from its beginning to its end. This means that a buffer memory is necessary in order to buffer-store a complete track portion that has been read backwards. However, buffer memories are already provided, in principle, in reproduction apparatuses for optical recording media for the purpose of buffer-storing data read from the recording medium, with the result that, in an advantageous manner, a buffer memory that is already present can also be used by extending it by the function of section-by-section bit reversal. In this case, the individual sections each correspond to a track portion that has been read in and whose address range is recorded in the buffer memory, or between which a section marking is inserted.
This advantageously enables double-sided recording media to be reproduced without any reversal of the direction of rotation or changing or turning over of the recording medium.
The reproduction of double-sided recording media without any reversal of the direction of rotation or changing or turning over of the recording medium can be carried out in reproduction apparatuses which scan on both sides and have a scanning device on each side of the recording medium or a scanning device which is moved or pivoted over from one side to the other side of the recording medium. Applicant""s advantageous arrangement for reproducing double-sided recording media does not necessitate firstly stopping the disc turntable and then accelerating it again in the opposite direction, since the reproduction of both sides of the double-sided recording medium is advantageously provided with the direction of rotation of the recording medium being maintained. The reproduction does not have to be interrupted and energy required for braking and accelerating the disc turntable including recording medium is saved.